In recent years, in order to improve information processing capability, changing electrical communication between electrical devices, such as integrated circuit devices, into optical transmission has been considered. For example, in Japanese Unexamined Patent Publication JP-A 2004-294857, is disclosed an optical transmission module in which an optical transmission body having an optical waveguide extended in a thickness direction of a substrate is mounted on a base through a guide pin. The optical transmission body is mounted on the base by inserting the guide pin into a guide hole for positioning which penetrates through the substrate in a thickness direction thereof.
However, in the optical transmission body described in JP-A 2004-294857, the guide hole is formed directly in the substrate. Consequently, there is a concern that a problem may occur, such as a positioning error in which the guide hole deviates from a predetermined position or a dimensional error in which the diameter of the guide hole deviates from a predetermined value. As a result, the guide hole formed in the optical transmission body has a constraint on a position or a diameter thereof.